The objectives of this work are to investigate the separate contributions of the retinal and choroidal circulations to retinal tissue oxygenation and to further develop a new angiographic technique which permits routine evaluation of the choroidal circulation in man. Using micro-electrodes, tissue PO2 maps will be made of the various retinal and choroidal layers of the living primate eye. These maps will be made under physiologically normal conditions of ocular circulation, with occluded choroidal circulation, and with and without hyperbaric oxygenation of arterial blood. A clinical evaluation of indocyanine green (ICG) fluorescence choroidal angiography will be continued. Following an intravenous injection of indocyanine green dye and a saline flush, a modified fundus camera which utilizes a continuous light source and a 35 mm motion picture camera photographs the ICG passage through the choroid at 5 frames per second.